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<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>计算器</title>
</head>
<body bgcolor="#c0c0c0">
	<h1>四则运算的计算器</h1><hr>
	<script type="text/javascript">
		function compute(obj) {
			obj.expr.value = eval(obj.expr.value)
		}
		var one = "1", two = "2", three = "3", four = "4", five = "5", six = "6", seven = "7", eight = "8", nine = "9", zero = "0";
		var plus = "+", minus = "-", multiply = "*", divde = "/", decimal = ".";
		function enter(obj, string) {
			obj.expr.value += string;
		}
		function clear(obj) {
			obj.expr.value = "";
		}
	</script>
	<center>
	<form name="calc">
	<table border="1" bgcolor="#c0c0c0">
		<tr>
			<td colspan=4><input type="text" name="expr" size=30 action="compute(this.form)"></td>
		</tr>
		<tr>
			<td align="center"><input type="button" id="button" value="  1  " onclick="enter(this.form, one)" style="border-style: double; border-width: 3px"></td>
			<td align="center"><input type="button" id="button" value="  2  " onclick="enter(this.form, two)" style="border-style: double; border-width: 3px"></td>
			<td align="center"><input type="button" id="button" value="  3  " onclick="enter(this.form, three)" style="border-style: double; border-width: 3px"></td>
			<td align="center"><input type="button" id="button" value="  +  " onclick="enter(this.form, plus)" style="border-style: double; border-width: 3px"></td>
		</tr>
		<tr>
			<td align="center"><input type="button" id="button" value="  4  " onclick="enter(this.form, four)" style="border-style: double; border-width: 3px"></td>
			<td align="center"><input type="button" id="button" value="  5  " onclick="enter(this.form, five)" style="border-style: double; border-width: 3px"></td>
			<td align="center"><input type="button" id="button" value="  6  " onclick="enter(this.form, six)" style="border-style: double; border-width: 3px"></td>
			<td align="center"><input type="button" id="button" value="  -  " onclick="enter(this.form, minus)" style="border-style: double; border-width: 3px"></td>
		</tr>
		<tr>
			<td align="center"><input type="button" id="button" value="  7  " onclick="enter(this.form, seven)" style="border-style: double; border-width: 3px"></td>
			<td align="center"><input type="button" id="button" value="  8  " onclick="enter(this.form, eight)" style="border-style: double; border-width: 3px"></td>
			<td align="center"><input type="button" id="button" value="  9  " onclick="enter(this.form, nine)" style="border-style: double; border-width: 3px"></td>
			<td align="center"><input type="button" id="button" value="  *  " onclick="enter(this.form, multiply)" style="border-style: double; border-width: 3px"></td>
		</tr>
		<tr>
			<td colspan=2><input type="button" id="button" value="  0  " onclick="enter(this.form, zero)" style="border-style: double; border-width: 3px"></td>
			<td align="center"><input type="button" id="button" value="  .  " onclick="enter(this.form, decimal)" style="border-style: double; border-width: 3px"></td>
			<td align="center"><input type="button" id="button" value="  /  " onclick="enter(this.form, divide)" style="border-style: double; border-width: 3px"></td>
		</tr>
		<tr>
			<td colspan=2><input type="button" value="  =  " onclick="compute(this.form)"></td>
			<td colspan=2><input type="button" value="  AC  " size=10 onclick="clear(this.form)"></td>
		</tr>
	</table>	
	</form>		
	</center>
</body>
</html>